Prostate-Specific Antigen (PSA)

Test Overview

A prostate-specific antigen (PSA) test measures the amount of
prostate-specific antigen in the blood. PSA is
released into a man's blood by his
prostate gland. Healthy men have low amounts of PSA in
the blood. The amount of PSA in the blood normally increases as a man's
prostate enlarges with age. PSA may increase because
of inflammation of the prostate gland (prostatitis) or
prostate cancer. An injury, a digital rectal exam, or
sexual activity (ejaculation) may also briefly raise PSA levels.

Why It Is Done

The prostate-specific antigen (PSA) test
is done to:

Screen men for prostate cancer. Since other common medical
conditions, such as benign prostatic hyperplasia (BPH) and prostatitis, can cause high PSA levels, a prostate
biopsy may be done if your doctor is concerned about signs of prostate cancer.

Check if cancer may be present when results from other
tests, such as a
digital rectal exam, are not normal. A PSA test does
not diagnose cancer, but it can be used along with other tests to determine if
cancer is present.

Watch prostate cancer during active surveillance or other treatment. If PSA levels increase, the cancer may be growing or spreading. PSA is
usually not present in a man who has had his prostate gland removed. A PSA
level that rises after prostate removal may mean the cancer has returned or has
spread.

How To Prepare

Before you have a prostate-specific
antigen (PSA), tell your doctor if you have had a:

Do not ejaculate for 24 hours before your PSA blood
test, either during sex or masturbation.

Talk to your doctor about
any concerns you have regarding the need for the test, its risks, how it will
be done, or what the results will mean. To help you understand the importance
of this test, fill out the
medical test information form(What is a PDF document?).

How It Is Done

The health professional taking a sample
of your blood will:

Wrap an elastic band around your upper arm to
stop the flow of blood. This makes the veins below the band larger so it is
easier to put a needle into the vein.

Clean the needle site with
alcohol.

Put the needle into the vein. More than one needle stick
may be needed.

Attach a tube to the needle to fill it with
blood.

Remove the band from your arm when enough blood is
collected.

Put a gauze pad or cotton ball over the needle site as
the needle is removed.

Put pressure on the site and then a
bandage.

How It Feels

The blood sample is taken from a vein in
your arm. An elastic band is wrapped around your upper arm. It may feel tight.
You may feel nothing at all from the needle, or you may feel a quick sting or
pinch.

Risks

There is very little chance of a problem from
having a blood sample taken from a vein.

You may get a small bruise at the site. You can
lower the chance of bruising by keeping pressure on the site for several
minutes.

In rare cases, the vein may become swollen after the blood
sample is taken. This problem is called phlebitis. A warm compress can be used
several times a day to treat this.

Ongoing bleeding can be a
problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and
other blood-thinning medicines can make bleeding more likely. If you have
bleeding or clotting problems, or if you take blood-thinning medicine, tell
your doctor before your blood sample is taken.

Results

The normal values listed here-called a reference range-are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.

Normal

Because normal PSA levels seem to increase
with age, age-specific ranges may be used. But the use of age-specific ranges
is controversial, and some doctors prefer to use one range for all ages. For
this reason, it is important to discuss your test results with your
doctor.

High values

A follow-up test that measures free prostate-specific
antigen (free PSA) may be used to see if a prostate biopsy should be done to
check for cancer. Free PSA is the percent of prostate-specific antigen that is not attached to proteins in the blood. The lower a man's free PSA percentage, the more likely he is to
have prostate cancer.

A man with a total PSA between 4 and 10 ng/mL may have a test to find out his free PSA, to see if cancer is likely to be present. This test can be very useful if he had a negative prostate biopsy in the past but still has a high total PSA.

Large doses of medicines, such as cyclophosphamide
(Cytoxan) and methotrexate for cancer
treatment.

The medicines dutasteride (Avodart) and finasteride (Proscar),
which are used to prevent further enlargement of the
prostate gland in men who have BPH, or the type of finasteride (Propecia) that is used for male-pattern baldness.

What To Think About

When combined with a
digital rectal exam, the prostate-specific antigen
(PSA) test may increase the chance of finding prostate cancer. To learn more, see the topic
Digital Rectal Examination (DRE).

A PSA
level within the normal ranges does not mean that prostate cancer is not
present. Some men who have prostate cancer have normal PSA levels.

Experts disagree about the type of testing that is appropriate if
the PSA level is high. The decision may depend on:

Results of your digital rectal
exam.

Results of any PSA tests you have had in the past. If your
PSA level gets higher in a short amount of time, follow-up testing may be
recommended.

Your age and health.

The costs and risks
of more tests and treatments.

Other prostate tests are being evaluated to
determine how well they tell the difference between prostate cancer and benign
prostatic hyperplasia.

The prostate-specific antigen density
(PSAD) test compares the PSA value to the size of the prostate gland. The size
of the prostate is measured using transrectal ultrasound
(TRUS).

The PSA velocity test is a measure of how rapidly PSA
levels increase over time. PSA levels increase more rapidly in men with
prostate cancer and more slowly in men with prostate enlargement (benign
prostatic hyperplasia).

A complexed prostate-specific antigen (cPSA) test may help show
if a prostate biopsy should be done. This test measures the amount of several forms of PSA that are attached to proteins found in the blood.

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